1. Field
Exemplary embodiments relate to a method and apparatus of reconstructing a three-dimensional (3D) image from two-dimensional (2D) images.
2. Description of the Related Art
Physical limits exist when measuring data for biological imaging in an x-ray tomosynthesis. Accordingly, a high spatial resolution and a temporal resolution may not be simultaneously obtained. Also, there may be trade-off relationship between spatial and temporal resolutions.
In Nyquist sampling, which is a signal processing theory in a conventional art, a number of pieces of measured data of a region of interest is required to be greater than the number of signals to be restored for a high spatial resolution. Also, measurement data, obtained at a speed two times faster than a movement speed of an object for imaging, is required for a high temporal resolution. Accordingly, a high spatial resolution may not be obtained in many cases.
In an x-ray tomosynthesis, a reconstruction method based on a signal processing theory in a conventional art may be performed when the number of pieces of measured data is equal to or greater than the number of data of an object to be reconstructed. Briefly, the shift-and-add method with respect to pixels of projected images may be used. Here, the pixels of projected images may correspond to three-dimensional (3D) pixels of an object along x-ray directions.
In an x-ray tomosynthesis, a movement angle of an x-ray generation tube may be limited according to physical characteristics of an object. In this case, when an object with high contrast exists and projected images are backprojected, a dim ghost image of the object with high contrast may be generated in tomosynthesis images. That is, since image information obtainable by Nyquist sampling that is required for exact reconstruction of an original image may not be provided with a limited movement angle of an x-ray generation tube, a ghost image may occur.
In a Nyquist sampling theory, which is a fundamental background of an information theory and a signal processing theory in a conventional art, possibility of exact reconstruction may be determined based on only a size of an original image.